1. Field of the Invention
The invention relates to catheter systems for delivery and/or retrieval of medical devices.
2. Description of Related Art
In many minimally invasive medical procedures, an introducer sheath or catheter is inserted in a blood vessel to gain access to a site within a patient's body for a diagnostic or therapeutic procedure, and used to deliver medical devices, including medical implants. Medical technology has produced a number of medical devices which are designed to be compressed into a first configuration, such as through a small diameter tube or catheter, in order to facilitate introduction through the vascular system, and to subsequently expand into an expanded configuration at a desired site in the body. For example, such devices can be intended to occlude defects or holes in the heart, such as intracardiac occluders, or to contact the walls of a passageway or blood vessel, in the case of vena cava filter or stents.
Among these devices, intracardiac occluders present special challenges for a delivery system. First, the occluder must be very carefully and precisely deployed at the treatment site to assure proper closure. Second, the tortuous anatomy of the cardiovascular system necessitates a delivery system capable of traversing the small radii of curvature of the vasculature and the confines of the heart chamber for delivery of the occluder to the deployment site.
Numerous systems for percutaneous catheter delivery of medical devices have been devised over the years in order to assist physicians in delivering and positioning medical devices within the human body in a minimally invasive manner. A common problem with many of these percutaneous delivery systems is that they can often adversely and unpredictably affect the position of the device upon deployment. For example, the released position of a medical implant may be different from its final position while still attached to the delivery system. In such case, the physician is forced to estimate the effect of this difference, compensate for this effect in positioning the implant, and take such effect into consideration when assessing final implant position prior to its release. Additionally, the movement of the implant that occurs following release from its delivery system can be unpredictable. Thus, the resulting improper positioning of such an implant can lead to unfavorable outcomes, such as a residual leak in the case of intracardiac occluders, or, in some extreme case, embolization of the implant.